TEM image analysis and modeling: application to boehmite nanoparticles

References

Maxime Moreaud, Dominique Jeulin, Vincent Morard, Renaud Revel
IFP Energies nouvelles,
rond point de l'échangeur de Solaize,
B.P. 3, 69360 SOLAIZE, France

Centre de Morphologie Mathématique,
Mathématiques et Systèmes, MINES ParisTech;
35, rue Saint-Honoré, 77305 Fontainebleau CEDEX - France

Abstract

Boehmite occurs in the form of nanoparticles. Upon drying, it can form the alumina that is common in catalyst support used in refining and petrochemicals. The topotactic transformation of boehmite alumina led to an interest in the precise shape and size of these nanoparticles which is highly linked to the catalyst activity. Boehmite nanoparticles can be observed by transmission electron microscopy. Although they are highly aggregated, the analysis of transmission electron microscopy images with a specific random model approach, here a dilution model, can give an accurate estimate of their size. To use this approach, electronic noise and diffraction artefacts on the edges of the nanoparticles have to be removed. Covariance measurements on micrographs can be performed. They can be used to fit a model. The fitting uses a novel numerical method to estimate the covariogram of grains. The model can take into account the specific orientations of the nanoparticles. The influence of noise, image filters used to remove noise and diffraction artefacts, as well as all the parameters of the model are all studied in this paper. We propose nanoparticle size estimations procedures based on both single and mixture-of-two particle models.

Paper

Journal information and copyrights

Journal of Microscopy (JoM), Wiley